The present invention relates to an electrostatic chuck mechanism and a charged particle beam apparatus, and particularly to an electrostatic chuck mechanism capable of effectively suppressing an influence of an electric field generated near an edge of a sample, and a charged particle beam apparatus.
Miniaturization of a semiconductor device progresses exponentially and a semiconductor device manufactured by a size of several tens of nanometer order becomes mainstream in recent years. In a manufacturing line for a semiconductor device having such a fine structure, an apparatus to which a scanning electron microscope is applied is used to perform a size measurement of a fine pattern or inspect defects of devices. For example, for the size measurement of a gate or a contact hole of a semiconductor device, a CD-SEM (Critical-Dimension Scanning Electron Microscope) is used, and for a defect inspection, a defect inspection SEM or the like is used. Further, also for a conduction inspection of deep holes for wiring, a scanning electron microscope is being used by a potential contrast.
In a charged particle beam apparatus typified by a scanning electron microscope, etc., an electrostatic chuck mechanism may be used as a holding mechanism for holding samples (semiconductor wafer and the like) as a target. An electrostatic chuck applies a voltage to a metal electrode provided therein, generates a positive or negative charge on surfaces of an object to be adsorbed and the electrostatic chuck, and fixes the object to be adsorbed by a coulomb force, etc. working therebetween. On the other hand, when an electrostatic chuck is adopted as a sample holding mechanism for an electron microscope, etc., a strong electric field formed between a sample and the electrostatic chuck may disturb a potential distribution in a periphery of a wafer (sample). As a result, there is the possibility that electron beams are bent and therefore cannot be irradiated on an appropriate position near the periphery of the wafer. In JP5143787 (US2012/0070066), disclosed is a method in which an adsorption electrode of an electrostatic chuck is made larger than the wafer and an electric field near an edge of the wafer is uniformized by an electric field generated by a portion protruding from the wafer. Further, in JP-A-2009-302415 (US2009/0309043), disclosed is an electrostatic chuck mechanism in which an electric-field correction part having the same height as that of a sample surface is arranged near a periphery of the sample.